In the prior art the end caps of the housing would cover the brush assembly but did not include protection against the brush mount screw from backing out. Also if the pair of brushes were enclosed, the shape was usually an inverted cup-shape, or some other type of plate or strip configuration. If individual or a pair of covers were used, it could be "L" shaped. In any event the cover did not fit within top and bottom housing extensions so as to provide both access to the brush assembly and improved strength and continuity of the housing.